STATUS - SOLD
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Description :
The Conrad Johnson Premier 7 was the first Zero-Feedback preamplifier from conrad-johnson. It was a true dual-mono preamp design with a separate external regulated power supply for each channel. The result was a mammoth preamplifier, housed in four separate chassis. Using 12 triodes (six per channel) in a zero feedback configuration provided extraordinary transient response not common in vacuum tube preamps. A low noise nuvistor input tube accommodated low output moving coil cartridges. A phono impedance selector was included for cartridge matching. New standards of circuit components were used in the Premiere Seven, including 300 micron linear-crystal solid silver internal wiring. Each channel had its own level control. Instead of traditional potentiometers, the level controls are actually stepped attenuators which switch discrete pairs of precision resistors. Special laser trimmed metal foil resistors were used throughout the audio circuit.
The Premier Seven was stunning in its ability to resolve inner detail, recreate a huge dynamic range, and extended frequency response while presenting the soundstage with incomparable accuracy. The Premier Seven-A offered a new phono stage circuit using a pair of nuvistors at the input. The resulting stage was even quieter, and capable of finer gradations in dynamics. The Premier Seven-B switched to machined oxygen free copper input/output jacks, upgraded internal wiring, and power supply resistors were upgraded to the same metal foil types used in the audio circuits.
Without losing to the original Premier 7's sonic performance, the Conrad Johnson Premier 7A is excellent in sound quality, with superlative soundstaging, ability to recreate spaciousness, and outstanding dynamics.
Specifications :
Type....................................................Vacuum-tube dual-mono preamplifier.
Inputs..................................................Phono (MC or MM), tuner, CD. Tape: 2 sets of inputs and 2 sets of outputs.
Outputs................................................2 sets, both phase-inverting, recommended for amplifiers with input impedance of 10k ohms or higher.
Level control.........................................23-position stepped attenuators with front-panel LED level indicators.
Tube complement.................................Two 6CW4s and four 6GK5s per channel.
Phono section
Gain....................................................40dB gain; overload in excess of 150mV at 1KHz;
RIAA equalization.................................±0.25db (20Hz–20KHz);
Hum & noise........................................80dB below 10mV input.
Line-level section
Gain....................................................29dB gain; 20V maximum output;
Bandpass............................................2Hz to more than 100kHz;
Hum & noise........................................88dB below 2.5V output;
Distortion.............................................Less than 0.25% THD or IMD at 1V output;
Output impedance................................Less than 200 ohms.
Dimensions(w x d x h)..........................48.5 x 42 x 19 cm
Weight................................................30 kg
Power Supply Unit
Dimensions(w x d x h)..........................48.5 x 41 x 10 cm
Miscellaneous :
Made in...............................................USA
Condition.............................................8 / 10 (Decent condition)
Product information :
http://www.conradjohnson.com/It_just_sounds_right/a-pr7.html
Reviews :
http://www.stereophile.com/tubepreamps/592cj/index.html |